Chair frame



FIG. 1 is a perspective view of a chair frame showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof; and

FIG. 5 is a left side elevational view thereof, the right side being a mirror image thereof. 

The ornamental design for a chair frame, substantially as shown and described. 